Adiabatic black hole growth in Sérsic models of elliptical galaxies

Abstract

We have examined the effect of slow growth of a central black hole on spherical galaxies that obey Sérsic or $R^{1/m}$ surface-brightness profiles. During such growth the actions of each stellar orbit are conserved, which allows us to compute the final distribution function if we assume that the initial distribution function is isotropic. We find that black-hole growth leads to a central cusp or ``excess light', in which the surface brightness varies with radius as $R^{-1.3}$ (with a weak dependence on Sérsic index $m$), the line-of-sight velocity dispersion varies as $R^{-1/2}$, and the velocity anisotropy is $\beta \simeq -0.24$ to $-0.28$ depending on $m$. The excess stellar mass in the cusp scales approximately linearly with the black-hole mass, and is typically 0.5--0.85 times the black-hole mass. This process may strongly influence the structure of nuclear star clusters if they contain black holes.

Submitted, 10 pages,13 figures in ApJ (2015)

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• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
• Multiple minor mergers: formation of elliptical galaxies and constraints for the growth of spiral disks
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Cited by in corpus (1)

• The secular evolution of a uniform density star cluster immersed in a compressible galactic tidal field